Illuminating structure.



PATBNTED JAN. 27, 1903.

P. .L. O. WADSWORTH; ILLUMINATING STRUCTURE.

AYPLIOATIOR PILED'IAB. 31, 1898,

I0 IODEL.

1m: mums Farms 00., wowumo WASHINGTON n. c.

NITE ST FRANK L. O. WADSWORTH, OF WILLIAMS BAY, WISCONSIN, ASSIGNOR, BY

MESNE ASSIGNMENTS, TO PRESSED PRISM PLATE GLASS COMPANY, A CORPORATIONOF WEST VIRGINIA.

iLLUWHNATING STRUCTURE.

SPECIFICATION forming part of Letters Patent No.

719,065, dated January 27, 1903.

Application filed March 31, 1898- Serial No; 675,973. (No model.)

To all 11/71/0122, it may concern:

Be it known that I, FRANK L. O. \VADS- WORTH, a citizen of the UnitedStates, residing at W'illianis Bay, in the county of Walworth and Stateof Wisconsin, have invented certain new and useful Improvements inIlluminating Structures, of which the following is a specification.

Many of the structures devised for illuminating rooms and spaces notaccessible to direct light from the illuminating source are effective indirecting a portion of the light by reflection or refraction into suchrooms or spaces; but owing to other characteristics or features ofconstruction the approximately perpendicular rays to the structurecannot pass without being deviated, and thus a part of the availableilluminating power is lost, and the possibility of Viewing objectsdirectly through the structure,as through an ordinary plain sheet ofglass, is destroyed. To overcome this objection to ordinaryilluminators, I make use of the principle that when light falls on asurface of transparent material at other than a right angle to thatsurface it is in part reflected and in part transmitted and that theproportion of the reflected light in comparison with the transmittedlight increases rapidly as the angle of incidence of the light on thesurface is increased; and I construct an illuminator with transparentblades adjusted at such an angle as to secure the desired reflectingaction of the surfaces thereof for the light-rays coming from theprincipal source of illumination and make these blades or plates ofuniform thickness or with parallel sides, so that the transmittedlight-rays can pass in direct lines into the room.

Various forms of structures may be employed in carrying out theinvention.

As shown in the drawings, Figure 1 illustrates one means of embodyingthe invention in an illuminating-panel. Fig. 2 illustrates a differentproportion of the illuminatingplates. Fig. 3 illustrates a form ofplates to avoid certain light deflections.

The general purpose of illuminating structures is to secure a moreuniform and efficient distribution of light in the room or space to beilluminated than is possible without their use. In windows opening onnarrow streets, alleys, courts, light-wells, &c., the larger proportionof the light available for daylight illumination comes only from theopening toward the sky at the top of the street or well and ordinarilyfalls directly on the floor at the foot of the window-opening, where,owing to the usually non-reflective character of the floor material, itis lost for generalilluminative purposes. Illuminating structures aregenerally so designed as to receive 'this light, and instead of allowingit to pass directly through unchanged in direction, as it does in thecase of an ordinary window-glass, to deflect it backward into the roomtoward the part of the space in which an increased illuminating effectis desired; but it also frequently happens when windows are near the topof the building or open on a wide well-lighted street that a largeamount of light comes from directions nearly perpendicular to thewindow-opening, as well as from the sky, and it is evidently desirableto be able to utilize this light, as well as that coming from above. Itis also in many cases desirable to obtain such a structure that while itacts as an illuminating structure when placed in a window or otheropening it will still not obstruct direct vision through such anopening, but will allow objects to be viewed through it with the samefacility as through an ordinary plain sheetof window-glass. Thisrequires a structure of such a nature as to deflect rays coming fromdirections considerably inclined to the plane of the structure and atthe same time allow those coming from directions more nearlyperpendicular to said plane to pass unchanged in direction. To securesuch a structure is the object of my present invention.

In the construction of Fig. 1, O O are the transparent plates, withparallel faces set, in each instance at such an angle to the generaldirection of the light-rays falling on the faces of the plates from theprincipal source of illumination that both the upper and lower facesshall act to a greater or less extent as reflecting-faces. At the sametime, owing to the transparency of the plates, they permit the directpassage of rays of light in other di- I00 rections with but little lossfrom reflection. Thus a ray of light falling from above on one of theplatessay in the direction of the line a a is reflected in part in thedirection of the line a and passes in part through the plate in thedirection a, parallel to its initial direction, falls upon the nextlower plate, and is there reflected in part into the room and in partpasses to the plate below. By a series of such reflections nearly all ofthe rays ct are finally reflected horizontally, or nearly so, into theroom. Rays approximately horizontal, such as those in the direction Z2Z2 12 are also reflected in part and in part pass through the plates.Thus the ray falling in the direction I) is partially transmittedunchanged in direction and partially reflected in the direction b ontothe upper face of the next lower plate and is there again reflected inpart on a line parallel to b, and in part transmitted. In this case alsonearly all of the. light is by these successive reflections ultimatelydirected into the room along lines parallel to the original direction ofincidence. Rays, such as b which fall on the reflectingstrips at nearlynormal incidence are almost completely transmitted, a very smallproportion being reflected. The edges of the blades, although sometimesnarrow, receive rays of light from the direction d, and these aretotally reflected by the upper and lower faces of each plate insuccession and are directed through the body of the same, as indicatedby the zigzag lines, and finally pass from the opposite edge in thedirection d, parallel to (Z. Such plates, therefore, act asilluminatjug-plates for rays coming from above and as ordinarywindow-panes for rays nearly perpendicular to the plane of thestructure. One can therefore look through such a pane with equalfacility to that with which he looks through an ordinary pane ofplate-glass. The plates 0 may be secured in position in any suitablemanner. I have shown them combined with glass guard plates B B, whichexclude dust, due, and thereby preserve the faces in proper condition,the whole being secured and sealed in a frame A. In some instances,however, the plates 0 may be on one side of a plate B, as shown in Fig.2, the other side uncovered, but being sealed when the article isapplied at this side to the plate of a window.

Where it is desired that the rays entering nearly horizontally shall allpass from the structure in the same direction, the upper or lower edgeparts of the blades extending above or below the horizontal lines andforming prisms2areobjectionable,asin such casearay entering in thedirection 0, Fig. 1, is refracted in the direction 0. This may beeffectually overcome by cutting away these prismatic edge parts, asshown in Fig. 3. Another remedy which maybe applied for certain anglesof inclination of the plates consists in extending the edge of one bladeto such a height as to overlap the position of the lower edge of theblade above, (see Fig. 2,) so that the prisms 2 of one blade correct thedeflections of the prisms 2 of the other. Naturally I avoid all of thesedefects so far as possible by making the blades as thin as practicable,and thus present as little edge surface to the light as may be.

It will be seen that by the arrangement of parallel but separatedtransparent blades, each with parallel faces, the rays of light passingto either face of any blade are both refiected or transmitted to otherblades, and finally all with little loss emerge from the inner side ofthe structure, while those which fall upon the edges of the plates arealso received at the inner side of the structure. It will also beevident that the upper and lower reflecting-faces and the edges of theplates are effectually protected by the plates 0 being sealed. in theframe between the plates 13 B.

I will not here claim, broadly, arranging illuminating-plates within asealed case; but

I claim 1. In an illuminating structure, a series of paralleltransparent plates each with parallel faces and parallel edges arrangedone above the other, inclined upward toward the lightreceiving face ofthe structure and separated by a distance exceeding the thickness of theplates, substantially as set forth.

2. In an illuminating structure, a series of inclined, paralleltransparent plates arranged one above the other, and separated by adistance greater than the thickness of the plates, the edges of eachplate being substantially perpendicular to the general plane of thestructure, substantially as and for the purpose described.

3. The combination in an illuminating structure, of a series ofinclined, parallel, transparent plates arranged one above the other,each with parallel faces and parallel edges and separated to permitlight-rays to fall upon the surfaces of the plates, and transparent sideplates sealed against the edges of the former plates, substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

FRANK L. O. WVADSWORTH.

Witnesses:

CHARLES E. FOSTER, W. CLARENCE DUVALL.

